Conventional DC power systems include a power source, DC power controller, and batteries. Conventional DC power controllers are well known. They typically use quick-charge methods, voltage regulation/conversion, and/or battery protection to prolong battery operational life and to accelerate charging time. Typical systems utilize switches between the power source and the battery with a power controller pulse width modulating (PWM) the switches to achieve power transfer from the power source to the batteries. In such systems, the batteries are quickly charged by the power source, are discharged to power a load, and then are quickly charged again.
Although conventional DC power control systems have proven generally suitable for their intended purposes, they possess inherent deficiencies which detract from their overall effectiveness and desirability. For example, conventional DC power control systems do not effectively use power from the power source when the power source voltage fluctuates and drops below a voltage level required to charge the batteries. Ineffective use of fluctuating power source voltage results in a loss in power conversion efficiency both in charging the battery and in driving the load. Thus, there is a need to increase the power efficiency of a DC power control system that receives a fluctuating power source voltage.